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Mouthparts

Mouthparts of honey bee worker (posterior view). After Michener (1974, fig. 1.6) [1]. The mouthparts are unfolded and spread apart. Most of the time they are folded behind the head and held together. See also mechanism of folding of the mouthparts.

The glossa is similar to a long cylinder. The diameter of the glossa is 185.0±1.5 micrometers at the base and 96.6±0.3 micrometers in the middle part. The glossa consists of segments. Length of one segment is about 23 micrometers. On apical part of each of the segments there are 16-20 hairs. The hairs on basal part of the glossa are stiff and short (32 - 63 micrometers long), whereas the hairs on the middle and apical part are longer (171.9±0.3 micrometers long) [3]. At the apex of the glossa there is a spoon-like flabellum. The mouthparts are cleaned with foreleg tarsi [4].

Ingesting liquid food by bees is based on mechanism of "viscous dipping" [5]. The tongue is extended and immersed into nectar. At this stage hairs on the glossa erect asynchronously [6][7] and trap the nectar [8], see also video [5]. The erectable hairs can increase the ability of a bee to collect nectar [3]. Next, when coated with nectar, the glossa is retracted to a tube formed from galeae and labial palpi. Then the nectar is sucked into pharynx. There are ridges on the inner wall of galeae which can reduce friction during drinking [9][10]. Honey bees are able to imbibe 1.8 microlitres of diluted nectar per second [11]. This rate is lower in case of higher concentrations of nectar [11]. It was suggested that the optimal for bees concentration of sugar in nectar, which is a compromise between energy content and intake speed is about 52% [5] but see [3]. There are sensory organs on the mouthparts which facilitate the food intake [12][13][14][15].